I don't think it will last that long, Dave. The CDC says:


Fauci seems comfortable being more specific than the CDC, but even he won't promise anything, of course. It's way too much to post here, ya gotta read the entire response.

https://www.msn.com/en-us/health/med...ng/ss-BB1bsOiD

Just a snippet:
But data from similar coronaviruses may provide some insight, according to the nation's leading immunologist. In the 2002 SARS outbreak, for example, those who came down with the virus were naturally immune for over a year, though their immunity eventually waned. "So the bottom line is we don't know right now how long it lasts," Fauci said of immunity from the COVID-19 vaccine. "But it likely would last for a full year's cycle."


A full year is better than nothing and certainly better than 90 days, but I don't read anything that even hints at more than a year.
MY CONCERN is that, while it is 'free' now, it won't be free every year. Given that it will take an unknown amount of years for it to mutate to the point of no real threat, I suspect we will be budgeting for this expense in future years.